Gas draft apparatus



Aug. 12, 1969 o. E. FIKE GAS DRAFT APPARATUS Filed July 25. 1967INVENTOR. DANIEL E. PIKE ATTORNEY United States Patent 3,460,819 GASDRAFT APPARATUS Daniel E. Pike, Louisville, Ky., assignor to AmericanAir Filter Company, Inc., Louisville, Ky., a corporation of DelawareFiled July 25, 1967, Ser. No. 655,815 Int. Cl. C21b 7/08; F23j /00; F23117/16 U.S. Cl. 266--31 3 Claims ABSTRACT OF THE DISCLOSURE Apparatus fordrafting hot gases in a metallurgical system including an improved wetcap arrangement cooperating with the discharge end of a hot gas conduitto selectively provide a gas treating liquid curtain and a liquid seal.

BACKGROUND OF THE INVENTION The present invention pertains tometallurgical apparatus and finds particular utility at the top andoff-takes of metallurgical furnace shafts.

In metallurgical furnace shafts, such as shafts of metal meltingcupolas, it is common to provide a wet cap arrangement adjacent thedischarge end of the shaft to cool the metal surfaces exposed to hotcupola gases. To selectively prevent emission of gases from thedischarge end of cupola and thereby permit bypass of such gases to a gascleaning system, it also has been common to provide a mechanical damperarrangement at the stack discharge. For the most part, such arrangementshave been comparatively complex in construction, installation, andoperation, not only requiring a substantial amount of costlyconstruction materials, but in addition, requiring a considerable amountof time in fabrication, construction and maintenance. Further, in suchpast arrangements when hot gases have been allowed to pass from thedischarge end of the stack into the atmosphere, such gases have beenheavily laden with gas contaminant materials.

SUMMARY OF THE INVENTION In accordance with the present invention, anew, useful, and unobvious draft apparatus for metallurgical furnaces isprovided which lends itself to ready and economical fabrication,construction and maintenance, utilizing a minimum amount of materialsand requiring a minimum of time for installation. Further, the apparatusof the present invention, in addition to providing a wet cap to cool themetal surfaces exposed to hot cupola gases, provides a means forselectively and alternatively affording a wet curtain through which thehot gases must pass to necessarily be scrubbed prior to entering theatmosphere. The apparatus of the present invention further providesmeans for insuring that the hot gases pass through the liquid curtainand a liquid seal to alternatively deter the hot gases from entering theatmosphere by way of the discharge end of the stack.

Various other features of the present invention will become obvious toone skilled in the art upon reading the disclosure set forthhereinafter.

More particularly, the present invention provides apparatus for draftinghot gases comprising: shaft means having a discharge end for flow of hotgases to atmosphere; liquid receiving chamber means surrounding theshaft means below the discharge end thereof; cap means posiice tioned inspaced relationship from the discharge end of the shaft means to permitpassage of gases therebetween; liquid discharge means cooperating withthe cap means to provide a liquid curtain through which gases flow toatmosphere; the cap means having a lower depending skirt portionextending therefrom into the liquid receiving chamber means; and liquidlevel control means cooperating with the liquid receiving chamber meansto selectively maintain a liquid level therein above the depending skirtportion of the cap means to selectively provide a liquid curtain and aliquid seal at the discharge end of the shaft means.

It is to be understood that various changes can be made in thearrangement, form and construction of the apparatus disclosed herein byone skilled in the art without departing from the scope or spirit of thepresent invention.

Referring to the drawing, there is disclosed a partially broken awayelevational view of one advantageous embodiment of the present inventionincorporated with a cupola-type furnace.

Cupola 1 includes a metal charging inlet 2 and stack shaft 3, the shaft3 having a hot gas bypass conduit 4 through which hot gases can beby-passed from stack 3 to suitable gas treating equipment known in theart and not shown. Since the present invention can be utilized with anyone of several types of metallurgical furnaces, cupola 1 is disclosed inits broadest form without details.

Arranged to surround shaft 3 below discharge end 6 thereof is liquidreceiving chamber 7. Disposed within chamber 7 in spaced relationshipabout discharge end 6 of shaft 3 is wet cap 8. Cap 8 includes an upperconical portion 9 and a lower depending skirt portion 11, which skirtportion extends above and below the discharge end 6 of the shaft intoliquid receiving chamber 7.

Positioned above conical portion 9 of cap 8 is liquid discharge conduit12, the conduit being arranged to discharge a suitable liquid such aswater at the apex of conical portion 9 of wet cap 8. Further positionedabove cap 8 in spaced relationship above liquid discharge conduit 12 isejector conduit 13. Ejector conduit 13 which can be connected in asuitable manner not shown to hot blast air from the cupola system or tosome other suitable hot blast air source is arranged to eject such blastof air along the direction of gas flow away from wet cap 8 as to provideadditional pressure to the hot gases emitted from stack 3 and thusovercome the resistance occasioned by wet cap 8 above the shaft.

As will be noted in the drawing, liquid chamber 7 is provided with aliquid level control means in the form of an upper valve 14 and a lowervalve 16. Valve 14 is selectively positioned above the bottom edge oflower depending skirt portion 11 of cap 8, while valve 16 is selectivelypositioned well below the bottom edge of skirt portion 11. Bycontrolling the relative open and closed positions of valves 14 and 16and the pressure through ejector 13, it is possible to selectivelyprovide a liquid seal for shaft 3, or alternatively, a wet scrubbingcurtain through which the hot gases necessarily must pass before beingemitted to atmosphere.

The invention claimed is:

1. Apparatus for drafting hot gases comprising shaft means having adischarge end for flow of gases to atmosphere; liquid receiving chambermeans surrounding said shaft means below said discharge end thereof; capmeans positioned in spaced relation from said discharge end of saidshaft means to permit passage of gases therebetween; liquid dischargemeans cooperating with said cap means to provide a liquid curtainthrough which gases flow to atmosphere; said cap means having a lowerdepending skirt portion extending therefrom into said liquid receivingchamber means; and liquid level control means cooperating with saidliquid receiving chamber means to selectively maintain a liquid leveltherein above said depending skirt portion of said cap means toselectively provide a liquid curtain and a liquid seal at said dischargeend of said shaft means.

2. The apparatus of claim 1 and aspirating means to selectively inducethe flow of gas around the depending skirt portion of said cap means.

3. The apparatus of claim 1, the upper portion of said cap means beingof conical configuration, said liquid discharge means being positionedto discharge liquid above the apex of said conical upper portion of saidcap means.

References Cited J. SPENCER OVERHOLSER, Primary Examiner JOHN S. BROWN,Assistant Examiner US. Cl. X.R.

l19, 26ll7, 121

